1. Field of the Invention
This invention relates to a filter system for large containers, in particular silos, comprising a hollow section containing at least one filter, one end of which is connectable to the large container and has an air inlet opening, while the other end has an air outlet opening in communication with the filter.
2. Description of the Prior Art
Conventional filter systems for large containers, in particular silos, are, as a rule, disposed on the top of the large container to trap dust particles generated and exhausted from the container during the course of filling the large container. A plurality of filter systems is secured to the roof of the large container, on which systems maintenance is performed at regular intervals. If the filter elements of the filter system become inoperative, they must be replace within a very short period of time. This is true, particularly, if they become inoperative during the filling of the large container.
Based on the above state of the art, it is the object of this invention to improve the filter system of the species without undue structural modifications such that replacement of the filter element(s) can be accomplished within a very short time.
This object is attained in accordance with this invention where the filter is inserted into the air outlet opening from the outside and is supported by a sealing flange on the edge of the exterior of the air outlet opening. The end of the hollow section having the air outlet opening can be covered with a dome. The dome is operationally connected to the hollow section and in communication with the air outlet opening. The dome is secured under pressure to the flange while in the operative position and, while in the inoperative position, leaves open the end.
In accordance with one embodiment of this invention, the hollow section, which is secured to the large container in an airtight manner, is equipped with at least one filter element which, on the one hand, is connected to the top side of the hollow section in an airtight manner and, on the other hand, is exchanged quickly and without problems. Preferably, the filter elements are cylinder-shaped bodies through which the contaminated and dust particle-containing air radially flows into the interior of the hollow section. The interior of the hollow section in turn, is in communication with the air outlet opening of the hollow section through which the air is exhausted. The filter elements may have a diameter up to 80 cm and a length of more than 100 cm. The dome, which as a rule has considerable weight, absorbs the pressure acting on the filter elements. A pressure wave is created when the large containers are filled, which has the potential of displacing the filter elements axially upward. Such movement of the filter elements is prevented by the dome.
In accordance with a preferred embodiment of this invention, the air outlet opening has a flange disposed in the interior of the hollow section, which radially surrounds the filter flange. The filter flange has a truncated cone-shaped section and an annular section. The annular section encloses the base of the truncated cone-shaped section and is designed to support the filter. To improve the connection between the flange of the air outlet opening and the filter flange, in accordance with another embodiment of this invention, the air outlet opening flange is interlocked with the truncated cone-shaped section of the filter flange.
To increase the pressure acting on the filter flange from the direction of the dome, in accordance with another embodiment of this invention, in the operational position of the dome, the distance of the dome from the air outlet opening side of the hollow section is less than the thickness of the filter flange. The filter flange is made preferably of plastic or rubber, while the hollow section and the dome are made preferably of metal.
In accordance with another embodiment of this invention, the opening of the dome is enclosed by a flange, protruding in the direction of the hollow section and in contact under pressure with the filter flange. As a result, the filter flange is clamped not only between the dome and the top side of the hollow section, but also between the flanges of the hollow section and the dome, providing an interlocking and frictional connection between these parts.
In accordance with still another embodiment of this invention, the dome is releasably connected to the hollow section by a hinge and a clamping device. In this connection these measures can also be taken by the dome being swivelable in a horizontal and/or a vertical plane by at least 90.degree.. Thus, the dome can be swivelled around a horizontal as well as a vertical axis.
In accordance with embodiments of this invention in which the filter system has a cylindrical or cuboid hollow section and a plurality of filter elements, a sealing ring, which surrounds the filter elements, is preferably clamped between the dome and the hollow section.
To prevent dirt from entering the outlet side of the filter elements, in accordance with another embodiment of this invention, the side of the dome facing the hollow section has a pressure plate with openings, the form of which approximately corresponds to the top side of the hollow section. Preferably, the pressure plate is connected to the dome by struts, between which the filtered air flowing out of the large container can reach the outside. The top side of the hollow section is thus surrounded on all sides, so that the air flowing vertically upwards through the filter elements is deflected on the inside of the concave dome and flows to the outside along the radial exterior of the hollow section.
To remove the dirt particles deposited on the radial exterior of the filter elements more easily, in accordance with another embodiment of this invention, nozzles, which are directed into the openings and are connected to a compressed air line, are provided between the dome and the pressure plate. If the radial inside of the hollow-cylindrical filter elements is charged with (clean) compressed air in a pulsed manner, the dust particles are loosened from the radial exterior of the filter elements and flow to the interior of the large container.